In order to realize miniaturization of devices such as semiconductor devices, a technique for forming a fine pattern by using a self-assembled material that self-assembles into an orderly pattern, i.e., a self-assembly technique, attracts attention as an alternative technique for a conventional lithography technique.
In the self-assembly technique, a target object is prepared by forming an organic polymer layer on a substrate and then forming a resist mask on the organic polymer layer. Next, the target object is exposed to a plasma generated in a plasma processing apparatus. Accordingly, the organic polymer layer is etched. Then, a resist mask is peeled off. Thereafter, a self-assemblable block copolymer layer is formed on the target object and a process that allows self-assembly of two polymers contained in the block copolymer layer is performed. As a consequence, two regions are formed on the block polymer layer. Lastly, a pattern is formed by selectively etching one of the two regions of the block polymer layer.
In the self-assembly technique, in order to peel off the resist mask, the target object is detached from an electrostatic chuck of the plasma processing apparatus after the etching of organic polymer layer and then transferred from the plasma processing apparatus to another apparatus.
When the target object is detached from the electrostatic chuck, it is general that a plasma of a rare gas such as argon gas or the like is generated in the processing chamber of the plasma processing apparatus. By destaticizing the target object while the target object is exposed to the plasma of the rare gas, it is possible to detach the target object from the electrostatic chuck while reducing stress applied to the target object. Such destaticization is disclosed in Japanese Patent Application Publication No. 1995-273093.
However, when the target object is destaticized in the plasma of the rare gas, impurities are adhered to the organic polymer layer. The impurities contain a substrate material, e.g., silicon. The impurities remain as residue even after the resist mask is peeled off. The organic polymer layer serves as a base layer for a block copolymer layer to be described later. Thus, if the block copolymer layer is etched in a state where the residue remains on the organic polymer layer, a pattern different from an initial pattern is formed.
Therefore, when the target object is processed, it is desired to suppress the generation of residue due to destaticization of the target object from the electrostatic chuck of the plasma processing apparatus.